Wave guide electrotherapeutic system



s. c. SOUTHWORTH 2,407,690

I WAVE GUIDE ELECTROTHERAPEUTIC SYSTEM Filed llay 16, 1941 Sept. 17, 1946.

4 Sheets-Sheet 1 OSCILLATOR mo mrurnen POWER mpsomc:

a n anon I wn'cu ADJUST- HARMONC E E APPARATUS COUPLER. ABLE l3 IAPPLICATOR I A v. FIGJ.

. INVENTOR By G CSOUTHWO RTH ii -w ATIDQNEY Sept. 17, 1946.

WAVE GUIDE ELECTRO'IHERAPEU'I'IC SYSTEM 6. c. SOUTHWORTH 2,407,690

4 Sheets-Sheet 2 Filed May 16, 1941 I IN VENT OR By a.c.sour/-/w0/?m A TTOR EY P 17,;1946- G. c. SOUTHWORTH 2,407,690

wm: GUIDE ELEc'rRoTnERAPEu'rIc sYs'rEu Filed lay 16, 1941 4 Sheets-Sheet s wvsmon By 6.6. SOUTH WORTH AUOR/VEV Sept. 17, 1946.

G. C. SOUTHWORTH WAVE GUIDE ELECTROTHERAPEUTIC SYSTEM Filed May 16, 1941 FIG. [0

4 Sheets-Sheet 4 ENTOR C. ZS O UTH WORTH Patented Sept. 17, 1946 WAVE GUIDE ELECTROTHERAPEUTIC SYSTEM George C. Southworth, Red Bank, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application May 16, 1941, Serial No. 393,756

This invention relates to apparatus for electrotherapeutic treatment and more particularly to such apparatus involving electric waves of extremely high frequencies.

Electric energy having wave-lengths of several meters has for some time been used for'deep penetration in what is generally known as diathermy. Very much higher frequency waves are also suitable for this purpose and there are indications that they may produce still other biological effects. It has been claimed that in particular frequency ranges these waves may kill certain harmful bacteria and that in others they may be used to destroy malignant tissue.

In the past it has been customary to apply electric wave power to affected tissues by placing the affected portion in so far as possible between two plate electrodes. For example, if a rheumatic knee were involved the two plates were placed on opposite sides of the joint. In the case of lumbago one plate was placed on the muscle involved and the other on the abdomen. With certain gland difficulties one plate has taken the form of a small flattened rod that was brought as near as possible to the affected part. The other plate retained its usual form and was ap-- plied at some nearby external point.

It is obvious that in cases such as have been mentioned, a large part of the wave power has gone to parts that are unaffected by the disease. An object of this invention is to increase the efllciency of electrotherapeutic treatments by restricting the application of energy to that part of the body which is in need of treatment.

Another object of the invention is to increase the efficiency of transfer of energy from the electric wave system to the body to be treated.

An additional object of the invention is to increase the safety of electrotherapeutic treatment by confining the energy applied to the region of the disease thus removing any hazards of deranging other portions of the body which are in normal condition.

An additional feature of the invention is the provision of applicators sufllciently small to enter orifices or incisions which are not large.

A still further object of the invention is to prevent wasteful dissipation of wave energy by refiection at the surface of a body to be treated.

Another object of the invention is to enable directive application of wave energy internally of a body so as to treat a particular portion without exposing unaffected portions to unnecessary excitation.

In accordance with the invention the energy of such high frequency electric waves as lend themselves to wave guide transmission is directed to a part in need of electrotherapeutic treatment by a wave guide which is terminated in an applicator having such physical configuration as is suitable for the part to be treated and having such wave 14 Claims. (Cl. res-422)- 2 transmission properties as to transfer wave energy with high efflciency to the aflected part which is to be treated.

All these objects and other features and advantages of the invention will become apparent upon consideration of the following detailed specification taken in connection with the accompanying drawings in which:

Fig. 1 illustrates a high frequency electrotherapeutic system; I

Figs. 2 to 9, inclusive, show modifications of the applicator;

Figs. 10 and 11 illustrate details of an applicator for sterilizing fluids; and

Fig. 12 shows a cabinet in which a therapeutic system in accordance with this invention may be housed.

Referring to Fig. 1, a source of high frequency oscillations 10 may be of any suitable type as, for example, a magnetron oscillator. Preferably it is of a type capable of producing oscillations rich in very high frequency harmonics. The oscillator is placed within a closed resonance chamber H so as to electrically excite the chamber at its resonance frequency. In order to tune the chamber II, a sliding tuner l2 and a telescoping cap I! are employed. This enables fixing the position of the connections of oscillator ill with respect to the chamber so as to secure the most effective coupling. The oscillator accordingly produces oscillations of a fundamental frequency determined by the tuning of the chamber l I, and harmonic oscillations. Opening into the chamber H is a wave guide IS the diameter of which is not large enough to permit oscillations of the fundamental frequency to pass. Under those circumstances oscillations of the lowest harmonic frequency which the wave guide I will pass are accentuated and transmitted by the wave guide to resonant terminal chamber l5 tuned by an iris l6 and a piston tuner I! to the desired harmonic.

The chamber I5 is connected to the input of an electronic amplifier IS. The output of the amplifler is associated with a resonant terminal chamber IQ of a second wave guide section 20 with which is associated a power measuring apparatus 2|, an impedance matching section 22 and an adjustable applicator 23.

The amplifier l8 comprises an evacuated envelope 24 preferably of dielectric material including an electron emitting cathode 25 of any suitable type but preferably one which will emit electrons in a well-defined central beam. An electron collector or anode 26 is located at the opposite end of the envelope 2|. The external circuits for exciting the cathode 25 and for polarizing the collector 28 with respect to the cathode may be of conventional type and are not illustrated. Electron beam focusing device 21 for assisting in collimating the beam may be of wellknown type. Circular discs 28 and 29 extend through and across the envelope 24 as extensions of the upper and lower surfaces of the resonance chambers i and I9. It will be understood that the resonance chambers l5 and I! may be of any suitable contour in their cross section perpendicular to the paper but, as illustrated, the chambers are rectangular parallelepipeds. Discs 28 and 29 are each provided with conical projections extending toward each' other and centrally apertured as at 30 to form short central gaps through the respective electromagnetic fields of the chambers l8 and I! in line with the central axis of the electron beam passing from cathode 25 to collector 26. In a manner which will be well understood to those skilled in the art. the electromagnetic fleld within the chamber II will set up alternating potentials across the gap between discs 28 to vary the velocity of the electrons passing therebetween. The electron beam after variation of its electron velocity passes down through a drift tube II of length sumcient to enable the velocity-varied electron beam to become charge-density varied at the time that it reaches the gap between discs 29. If desired, the central dielectric portion of the envelope 24 between the inner discs 28 and 29 may be omitted and replaced by the metallic drift tube. In a manner also well known to those skilled in theart, the charge-density varied beam traversing the gap between the discs 29 reacts with the electromagnetic field in the chamber It to transfer energy from the beam to the field. In this manner, the harmonic oscillations selected by the wave guide l4 and the resonance chamber i5 actuate the amplifier II to impress upon the resonance chamber l9 oscillations of corresponding frequency and wave form but of greatly augmented intensity. These amplified oscillations are supplied by the resonance chamber It to the wave guide 20. The resonance chamber I2 is provided with a coupling iris 22 and a, tuner 22 similar to those 01' the resonance chamber II.

The power measuring apparatus 2| is similar to the structure illustrated in Fig. 5 of the U. 8. Patent 2,106,713 issued February 1, 1938 to A. E. Bowen. It comprises a tubular chamber 24 mounted to slide longitudinally along a slot 35 in the wave guide 20 and provided with a shielding cover 26 to overlie the entire slot regardless of the position of the chamber 24. Supported along the central axis of the chamber 24 is a conductor 31 including in series a wave detector 28 preferably of the crystal detector type. Conductor 21 passes through the central portion of a supporting disc 29 of dielectric material and also through a central axial hole which it closely fits extending through tuner 40 and its adjusting screw 4|. A free end 42 of the conductor 31 proiects down into thewave guide 20 and serves in the manner of a small pick-up antenna to receive energy from the electromagnetic wave propagated through the wave guide. The tuning of the antenna comprising that portion of the conductor 3'! beneath the tuner 40 is effected by manipulation of an internally threaded nut 43 retained in position by a lug 44 and engaging with the threads of the adjusting screw 4| which is attached to the tuning plunger 40. The detector 28 is electrically connected to an indicator 45 through the conductors 21 and 4|, the conductor 40 passing through an insulating eyelet in the wall of chamber 24. A high frequency choke 41 may be included in the conductor 40. If the crystal response is proportional to the current in the pick-up antenna, the dial of the indicator 45 may be readily calibrated as to show the magnitude of wave energy passing the pro- Jecting antenna tip 42. In use, chamber 24 of the wave power measuring apparatus is moved along the wave guide and the indications of the indicator 45-are carefully observed. If these vary with the position of the chamber from a maximum in one position to a minimum in another, it is an indication that standing waves are being set up in the guide 20 by reflections occasioned by lack of an impedance match at some point. Accordingly, steps may be taken to read- Just the various couplings and, particularly, that of the absorbing load 50 as to produce an impedance match and reduce such reflections.

When final indication .of the indicator 45 is found at the position of minimum indication which will' represent the power passing from the source to the applicator or load and not 1 returning. Thereafter the dosage or the amount of energy supplied to the load may be varied by varying the output of the oscillator l0 and the indicator will yield a corresponding indication.

Beyond the power measuring apparatus the impedance coupler section 22 serves to connect the guide 20 to the applicator 23. The applicator is designed to apply the guided wave energy to a body to be given electrotherapeutic treatment. The applicator comprises a core 49 of dielectric material to enable its dimensions in a thickness direction to be made as small as possible consistently with the wave-length used. Assume, for example, that the core 49 consists of ceramic material coated with sprayed metal or deposited metal as indicated at 50. A portion 5| of the core is left uncoated and is normally covered by a rotatable metallic sheath 52 to which a manipulating handle 52 is fixed. The sheath i2 is provided at its inner end with a bearing portion supported on an annular bearing flange 54 on the outer surface of the wave guide structure. Upon bringing the applicator into an incision the sheath 52 is rotated to expose aflected tissues to wave energy radiated through the uncoated portion SI of the core. In this way the treatment may be confined to a particular zone or spot thus conserving the energy and preventing deleterious action upon unailected parts.

The impedance coupler section 22 is designed to match the impedance of the guide 20 and the applicator 23. The core 49, at its inner end is conical and dimensioned so that the solid dielectric material increases its thickness as the diameter or the impedance matching section 22 of the hollow wave guide 20 decreases.

Fig. 2 illustrates a modified impedance matching coupler and applicator which may be substituted for the elements at the right of section line 2-2 of Fig. 1. The impedance matching coupler 55 of Fig. 2 is a tunable resonance chamber provided with two slide tuners 58 and 51. These enable the chamber 55 to be given the proper tuning and at the same time enable the position of the applicator dielectric plate 58 to be properly fixed with respect to the chamber in order to secure the desired coupling between it and the chamber.

Another problem involved is that of the desi n square of the amplitude or the high frequency 76 of the app i t r r lative to th imp da of thetissuesorbodytobetreated. 'I'heapplicatlon oi the open end of a wave guide to an aflected part is a very simple expedient which is preferable to the present-day electrostatic plate method. when using the terminal or a wave guide as an applicator the greatest amount 0! power i transferred to the tissue when the im- 6 posited metal. For semiflexible material the covering may be metal fabric such as is commonly technique.

The applicator oi' Fig. 4 consists of a ceramic core I! covered by a retractible metallic sheath ll. when the apparatus is not in use the sheath pedance of the tissue matches that of the g ide. extends over the core sufliciently far that no that is, when there are no serious reflections at waves are transmitted. It is held in its normal the Junction oi the guide with the flesh. Tissues 10 position by a spiral spring 65. By means of the consist mainly of water and hence may be thought of as high dielectric constant materials.

in Fig. 4, to a point where wave power begins to It is probable that they have considerable dielecflow and the meter connected to the movable detrlc loss. This indicates that in general for a tector indicates the required output. In general, proper match a guide of high dielectric constant, it will be found that the sheath pomtions to give preferably K=80 or more, should be used. The appreciable amounts of power output occur at use of such a material also tends toward a smaller half wave intervals and that one or possibly two and more convenient guide. Inasmuch, however, of the e exposed int rvals will be suflicient, This as tissues vary somewhat in their W r content. distance will, 0! course. depend upon the irethey difl'er also in dielectric constant. It is. quencies used but for a lo centimeter wave it therefore.- des ab e t p e a system in which will be found to be but a fraction of an inch. he ppar us i fairly flex l in i application- In a modification the sheath may be interior- Fi 3 illustrate! an expedient for inhibitln! ly threaded at its inner end to be retracted by reflection from tissues. A wave guide 89 may be e ti o! the hollow open-ended type is provided near This form of applicator is adaptable to the its end with an iris I whichmay be moved longitreatment of semiexposed glands such as tonsils, i l y w d y from e open end 01' or if it be made sufliciently small and flexible it the guide. Thus the end section or the guide may actually be passed through small ducts to constitutes in eflect a resonant chamber termiaflected parts as, for example, through nasal pasnated by the tissue to which the open end is apsages to sinuses.

plie Th ri m y be moved until the D Fig. 5 illustrates an applicator similar to that cat de ce indicates t h e 18110 1151160 of Fig. l but with the sheath made up with a tlon oi the wave energy- If, however, the P hinged section 61 operated by a small rod 68.

t to which the en y is appli d 18 n t thick there Fig. 6 shows how the open end of a wave guide m y e a beam f W energy Passing through may be modified to facilitate application of wave the body under treatment with reflections at the energy to the back. The design is intended to in surface 1' h i To Prevent thi! promote comfort by allowing the patient to lie in a short section ii of wave guide similar to that his numa] dorsal position The applicator 1 r guide 59 may be placed behind the port under separate unit is to which the waveguide leading treatment in alignment with guide 5! and its to the power supply is connectedplt is intended t nin pi t n 62 may b adjusted until no reflecto he slipped into a bed under the. patient. Estakes P at the back 3801118 time, sentially it is a hollow chamber perhaps 15 inches surface. across and 2 inches deep with all sides except the 4 illustrates applicaml' mmfiwhat 511m top screened with metal. The top side may be that of E 1 treating internal parts covered with any one of several interchangeable the body. To make the dimensions oi the app sheets Ill of electrically conducting material, each as small as Wssible the thin the having a hole ll of diflerent proportions from guide may be a medium f dielecthe thers wave energy my pass trlc constant such as 8- ceramic loaded with titafrom t chamber to t body In practical use nium dioxide as, for example, the compositionsw the operator selects the cover sheet having an sold under the names of Al Si Mag 190'" and m of dimensions a to fiat f the area Condensa." This material has a dielectric cona 'lf The i fl made semi.

slant ranging from to 100 and consequently flexible and are coated with rubber. Since the permits use Of guides that range from one-ninth chamber may be tl distorted by t ht me-tenth the diameter of guides 5 of the patient an iris n is provided for tuning mg a similar frequency 31151111551 rangeand is made adjustable in both position and in example, ceramic guides suitab for diameter. Adjustable diameter irises are so well meter waves (i=3000 megacycles) need be but a kno i th cal h m quarter 01' an inch in diameter. Stated another g; zg zg g zi c m as to way, a guide of this kind 1 inch in diameter may pm 7 is an example of how the o n end of a be used for applying waves as long as 40 centiwave guide may be modified to g: more com meters megacycles) venient to treat a knee'joint A large part of the Ceramic materials are, in general, inflexible applicator 13 is made of solid metaL This and this may be unsuitable 9 vides a chamber of more or less flxed dimensions cators for certain purposes. When flexibility is and also a suitable connection to the pipe necessary it may be had by breaking the rod leading to the wave energy source. Outside of the suitable length and stringing solid portion or the applicator 13 there is another them on an manning The t semiflexible part 16 made of metal fabric. The rormance will be be f one end each bead latter provides a better lit to the irregularities oi gwwhw gg t end is 7 the knee. The entire apparatus may be coated aryhemis c na cav orcup fash on. Flexibi ity y a o 8% g with rubber both for convenience of application the guide 0! rubber and loading it with titanium dioxide. Metallic coverings for these ceramic guides may be metal pipes, sprayed metal or detight barrier 11 consisting of a tightly fitting but electromagnetically transparent disc may be placed over the end of the input pipe. With a used for shielding conductors in high frequency.

grips ii the sheath may be retracted as indicated and also for appearance and comfort. An air-,

connecting pipe 18 leading to an exhaust pump the air may be partly removed thus causing the flexible portion 16 to cling tightly to the flesh.

In Fig. 8, there is shown an applicator comprising a wave guide 88 terminating in a flat chamber 8| of circular conformation as viewed from above. To afford a convenient grip a thumb-hold 82 integral with the casing of chamber 8| is provided. The chamber 8| carries an applicator 83 resembling the usual hypodermic needle employed by physicians. This comprises a very small hollow metallic pipe 84 sharpened at its lower end as at 85 and the interior of which is filled with a needle 86 of dielectric material such as titanium dioxide. The needle 86 may have an internal diameter as small as 8.1 millimeter. The

hollow pipe 84 of the applicator 83 is mounted to slide longitudinally within a cylindrical member 81. It is maintained in its normal position by an internal compression spring 88 of a wellknown type which is retained between abutments on the mov ble pipe 84 and the cylindrical portion 8'! of t e applicator. A cap 88 threaded into the wall of chamber 8| carries the needle 88 and may be unscrewed from its position to remove the needle 86 when desired. When the device is to be used the tip of the applicator 88 is placed in contact with the flesh of the patient in the region of the affected part, the operator grips the thumb-hold 82 and the finger-holds 88 and presses the chamber 8| downward thus forcing the applicator through the flesh to the affected part. The finger-holds are attached to the sliding pipe of the applicator by pins 8| passing through slots in the stationary cylindrical member 81. The pins 9| also serve to hold the shell 84 from being forced outwardly by the spring 88 beyond a desired limiting position. After the tip of the applicator 83 has been forced to the position of the tissue to be treated the fingerholds 88 are squeezed toward the thumb-hold 82 thus retracting the pipe 84 toward the chamber 8| and exposing the tip of the dielectric core 88 to permit high frequency guided wave energy to be readily transmitted to the affected tissue.

Fig. 9 shows a modification of the disclosure of Fig. 8 in which the cap 89 and the needle 88 carried thereby have been removed and replaced by a funnel 82 provided with threads to screw into the wall of the shell 8|. The funnel carries a glass tube 93 extending well down past the spring 88 and fitting closely within the pipe or shell portion 84 of the applicator. The funnel may be filled with an aqueous solution of high dielectric constant to constitute a guide from the chamber 8| to the tip of applicator 83. A metallic screen 84 across the lower part of the funnel permits filling the funnel 82 and the pipe 84 and at the same time precludes loss of electric wave energy from the chamber through the funnel. It will be understood that the internal diameter of the pipe 84 i suihciently small to retain the dielectric fluid by capillary action. Upon insertion of the applicator in the tissue to be treated energy may be applied from chamber 8| over the guiding path co stituted by the pipe 84 with its liquid dielectric filling. As in the case of the device of Fig. 8 the pipe may be retracted to facilitate the energy transmission transfer between the guide and the tissue to be treated. In eflect the pipe 84 is not retracted from the tissue but chamber 8| is brought closer to the tissue forcing the dielectric liquid within the shell 84 into most intimate contact with the tissue.

. electric wave energy for sterilization and pasteurization oi. fluids. Wave guide apparatus of the general type disclosed offers numerous advantages over ordinary electric apparatus and circuits in these processes. If the fluid be a gas with substantially the same dielectric constant as air it will be sufllcient to circulate the gas through a resonant chamber in which radiation of will-- clent intensity prevails. If, however, .the fluid to be treated be a liquid the design must take into account the dielectric constant and the losses presented by the substance to be treated. For purposes of illustration we shall assume that the materlal to be treated is water and that its dielectric constant is 8|. An apparatus suitable for such a treatment is shown-in Figs. 10 and 11.

Referring to Figs. 10 and 11 a resonant metallic chamber 88 similar in general to the resonant chamber II of Fig. l is shown open at its left end for connection to a wave guide. A sliding tuning device I88 is provided for reasons which will be apparent. The chamber 99 is divided into two parts by means of two rather closely spaced metal partitions IN and I82. Between the partitions IM and I82 a sterilization cell I83 shown in detail in Fig. 11 passes transversely through the chamber 88. It comprises a rectangular fluid conduit having an inlet I84 for liquid to be sterilized and an outlet I88. Openings in the partitions IN and I82 of an area roughly one-ninth that of the area' of each partition expose the liquid to electromagnetic wave energy which readily passes through windows I86 of low loss dielectric material which. correspond to and are contiguous with the opening. To prevent escape of wave energy beyond that portion of the sterilizing cell between the windows, and screens I81 and top and bottom metallic walls I88 are provided to permit flow of the fluid to be sterilized. This construction insures that there be a suflicient intensity of the wave energy between the windows I86 to kill germ life. The proper position of the dividing partitions IN and I82 along the length of the chamber may be determined experimentally. The plunger I88 may assist in obtaining the most effective position for the sterilization cell relative to the length of the chamber.

Fig. 12 illustrates a portable cabinet assembly of a typical electrotherapeutic system in accordance with the invention. The three meters I88 indicate respectively plate voltage, plate current and filament current of the oscillator or the amplifier, as desired. For the circuits of each of these currents, there is a corresponding regulating knob II8. A meter 45 serving as a power indicator, as already explained in connection with Fig. l is also provided. Switches III respectively close the filament and plate current circuits. An indicator II2 similar in appearance to the frequency tuning indicator of an ordinary broadcast receiver is connected by a flexible wire through the rotatable control knob II3 to the movable chamber 34 of Fig. 1 carrying the detector 38. This facilitates moving the power measuring apparatus along the length of the wave guide.

The cabinet may be provided with an output wave guide section made up of a continuous spiral of interlocking metal strip so arranged as to provide a moderate amount of flexibility. It is permissible to employ 20 feet or more of this tubing if desired, since moderate bends do not materially affect the transmission. Inasmuch as the cabinet is mounted on wheels and the output guide is flexible the apparatus may be convenient- Sometimes it is desired to utilize high frequency 78 ly employed in almost any location. The basic 9 power supply may be provided by means of a plug and cord of conventional type cooperating with a socket Ill in the cabinet and the customary rectifier filter may be mounted in the cabinet or the cabinet may contain batteries to energize the ap' paratus.

What is claimed is:.

1. A wave guide system for electrotherapeutic treatment by high frequency waves comprising a tubular member having an electrically conduct- .ing surface to confine high frequency energy guided thereby. the diameter of the member being or the order of one-fourth inch, whereby the member may be inserted in small orifices or incisions and a fllling within the tubular member of a finely divided substance having a high dielectric constant to increase the wave-length which the tubular wave guide is capable of handling.

2. A system for transfer of electric oscillation energy comprising a source of electrical oscillations, 9. wave guide having an input portion connected to the source, an energy transfer element connected to another portion of the guide, the

transfer element having a terminating dielectric core which may be projected within a zone to which oscillation energy is to be transferred. a slidable electrically conducting sheath thereover to substantially enclose the core, and means whereby the sheath may be slid longitudinally to expose more or less or the core to control the amount of energy transferred from the dielectric to the surrounding zone.

' 3. A sterilization system comprising a fluid conduit, electric wave energy screens permeable to the fluid placed transverse to the direction of fluid flow, the conduit between said screens comprising two opposing wails of dielectric material to permit passage of electric wave energy transversely through the fluid in the zone between the screens, and the remainder of the conduit between the screens comprising electrically conducting material whereby the screens and the surfaces surrounding the zone between the screens may serve as a section of an electric wave uide.

4. A wave guide for directing electric wave energy to mass to which the energy is to be applied, an applicator for terminating the wave guide and for transferringenergy to the mass comprising a core of dielectric material having a portion of its periphery coated with conducting substance to prevent escape of energy, a movable conducting sheath normally covering the uncoated portion of the applicator, and means for moving the sheath to expose a desired part of the uncoated portion to permit outflow of energy therethrough.

5. An appliance comprising a wave energy directing system for bringing wave energy to a body to which it is to be applied, a wave energy applicator connected to and serving to terminate the directing system and consisting of a hollow conducting member having a contour adapted to fit the surface of the body, and means for exhausting the atmosphere from within the applicator to cause it to hold tightly against the body whereby unwanted leakage of wave energy between the applicator and the body is prevented.

6. An appliance in accordance with claim 5, characterized in this that the periphery of the applicator fits against the body and is flexible to accommodate itself to varying conformations.

7. A system comprising a source of electric wave energy, a tubular dielectric guide connected to said source for-brlnzlns wave energy to the surface of a body upon which the energy is to be impressed and means connected to the guide for inhibiting energy reflections at the surface of the body, said means including a controllable iris within the wave guide by which the impedances of the surface of the body nearest the guide and that or the guide maybe matched.

8. A system comprising a source of electric wave energy, a dielectric guide connected to said source for bringing wave energy to the surface of a body upon which the energy is to be impressed and means connected to the guide for inhibiting energy reflections at the surface of the body, said means including a tunable reflector which may be placed beyond the body as viewed from the transmitting system whereby energy refiections at the remote surface of the body be prevented.

9. A system comprising a source of electric wave energy, a dielectric guide connected to said source for bringing wave energy from the source to the surface of a body upon which the energy is to be impressed, and means connected to the guide for inhibiting energy reflections at the surface of the body, said means comprising a device on each side of the body under treatment whereby one device inhibits reflections or wave energy as it enters the body on the one side and the other inhibits reflections of wave energy as it leaves the body on the other side.

10. An electrotherapeutic appliance comprising a tubular needle of electrically conducting material adapted to be forced into the flesh in the region of an aifected part and means for supplying electric wave energy to the tubular needle at one .end whereby the energy may be guided by the dielectric within the needle serving as a dielectric guide and applied at an'interior point in the flesh at which the afiected part is locatedf ance with claim 10, characterized in this that the tubular needle is provided with a solid dielectric core.

18. An electrotherapeutic appliance in accord-.

ance with claim 10, characterized in this that the tubular needle is provided with a dielectric core comprising fluid material.

14. A system for application of electric wave energy to a mass comprising a source of electrical oscillation of the order of a few centimeters wavelength, a tubular wave guide by which the energy of the electrical oscillations is directed to the mass, the source and the wave guide having an electrically conducting sheath wholly surrounding the source and the wave guide except at the terminal of the wave guide remote from the source to prevent unwanted escape of energy, an

opening in the wave guide near said remote terminal thereof, a movable conducting closure for the opening, the portion of the guide in the region of the opening having a core of dielectric material whereby the cross sectional dimension of the guide and the area of the opening may be considerably reduced, and means for controlling the position or the closure to regulate emanation of wave energy through the opening to the mess.

' OIOMI C. WORTH- 

